Don't use substring() for a simple prefix match

third_party/WebKit/Source/core/svg/SVGTests.cpp

Index: third_party/WebKit/Source/core/svg/SVGTests.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGTests.cpp b/third_party/WebKit/Source/core/svg/SVGTests.cpp
index e0de9b933f7a42cbb6ab1b6723961163668126c6..4defe6cccdb14d01e9574b9a35823992bdedb4de 100644
--- a/third_party/WebKit/Source/core/svg/SVGTests.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGTests.cpp
@@ -51,15 +51,12 @@ bool SVGTests::isValid() const
 
     if (m_systemLanguage->isSpecified()) {
         bool matchFound = false;
-
-        const Vector<String>& systemLanguage = m_systemLanguage->value()->values();
-        for (const auto& value : systemLanguage) {
-            if (value == defaultLanguage().getString().substring(0, 2)) {
+        for (const auto& value : m_systemLanguage->value()->values()) {
+            if (value.length() == 2 && defaultLanguage().startsWith(value)) {
                 matchFound = true;
                 break;
             }
         }
-
         if (!matchFound)
             return false;
     }